Method of manufacturing stamped antenna

ABSTRACT

A method of manufacturing a stamped antenna includes providing a sheet of metallic material for a first partial stamping that forms an antenna including at least one pilot hole, traces, contacts, carriers connected to the traces, and tie-bars between the traces. The antenna is placed on a fixture having at least one fixture pin that is inserted through the at least one lot hole. A pressure sensitive adhesive including at least one die cut hole is placed on the fixture, with the fixture pin being inserted through the die cut hole aligning the antenna and the pressure sensitive adhesive such that an adhesive region of the pressure sensitive adhesive is positioned on the traces of the antenna. The pressure sensitive adhesive is then bonded to the traces of the antenna. A second complete stamping is then performed on the antenna, including pressure sensitive adhesive, to remove the carriers and tie-bars.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a stamped antenna and a method ofmanufacturing a stamped antenna, and more specifically, to a method ofmanufacturing an antenna that includes a first partial initial stampingof the antenna from a sheet of metal, and a subsequent complete stampingof the antenna.

2. Related Art

As communication technology continues to advance, the use of antennas isbecoming more widespread and possible applications are broadening.Various types of antennas are not only used for large scalecommunication, but also for small scale communication between devicesfor identification purposes and even for electronic device charging.

Near field communication (NFC) devices are becoming popular fortransferring data between two devices that are in proximity of eachother. NFC establishes a radio connection between two devices having aNFC antennas, such as smart phones, as well as NFC tags, which areunpowered devices that contain a NFC chip having a NFC antenna. NFCdevices, when in close proximity, can engage in two-way communicationwith one another. This two-way communication allows the devices totransfer data back and forth. Additionally, a NFC device can engage inone-way communication with a NFC tag, such that the NFC device canobtain data from the tag, but cannot transfer information to the tag.NFC tags can be employed for managing the inventory and sale of a widevariety of goods, as well of identification of data pertaining to goods.Accordingly, NFC tags may be used for retaining data that a user canobtain through engaging the tag with a NFC device.

Similarly, radio frequency identification (RFID) tags are findingincreased and widespread use as more systems are developed and placedinto service for managing the inventory and sale of a wider variety ofgoods. These RFID tags are applied to the goods and employ electroniccircuitry responsive to radio frequency (RF) signals for providingreadily monitored identification data relating to the goods.

NFC devices, NFC tags, and RFID tags all include an antenna connected toother circuit components. Because there is pressure to keep devicessmall, it follows that it is desirable that the antennas for thesedevices are compact and thin, resulting in antennas having thin widths,and narrow traces with small spacing between the traces. As technologyadvances, the desire for even more compact articles carrying NFC andRFID antennas increases.

NFC and RFID antennas typically occupy a substantial portion of the areadimensions of the article employing the antenna, and are oftenconstructed of a relatively thin copper foil for flexibility and formaximum effectiveness. Many antennas are currently manufactured by aprocess involving photochemical etching. The photochemical etchingprocess can often be expensive compared to other metal workingtechniques.

Accordingly, what would be desirable, but has not yet been provided, isan improved antenna and method of manufacturing.

SUMMARY OF THE INVENTION

The present invention relates to a stamped antenna and a method ofmanufacturing. A sheet of metallic material is provided and a firstpartial stamping is performed on the metallic material. The firstpartial stamping forms an antenna including traces, contacts, carriersconnected to the traces, and tie-bars between the traces. A pressuresensitive adhesive is then bonded to the traces of the antenna. A secondcomplete stamping is then performed on the antenna, including pressuresensitive adhesive, to remove the carriers and tie-bars.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing features of the disclosure will be apparent from thefollowing Detailed Description, taken in connection with theaccompanying drawings, in which:

FIG. 1 is a diagrammatic illustration of a sequential manufacturing linefor manufacturing an antenna;

FIG. 2A is a top view showing a near field communication antenna biscuitof the present disclosure after a first stamping;

FIG. 2B is a top view showing an example of a single near fieldcommunication antenna of the present disclosure stamped for a firsttime;

FIG. 3A is a top view of a pressure sensitive adhesive pad of thepresent disclosure;

FIG. 3B is a perspective view of the pressure sensitive adhesive pad ofFIG. 3A with the release liner partially removed showing the pattern ofadhesive;

FIG. 3C is a top view of the pressure sensitive adhesive pad of FIG. 3Awith the release liner fully removed showing the pattern of adhesive;

FIG. 4 is a perspective view of a fixture for receiving a pressuresensitive adhesive and first stamped antenna for further processing;

FIG. 5 is a perspective view the pressure sensitive adhesive pad of FIG.3C on the fixture of FIG. 4;

FIG. 6 is a perspective view the near field communication antennabiscuit of FIGS. 2A-2B on the fixture including the pressure sensitiveadhesive of FIG. 5;

FIG. 7 is a top view the near field communication antenna biscuit ofFIGS. 2A-2B and the pressure sensitive adhesive of FIG. 5 on thefixture;

FIG. 8 is a perspective view of the release liner being placed on thenear field communication antenna biscuit that has been placed onto thefixture;

FIG. 9 is a top view of the near field communication antennas andrelease liner after a second stamping;

FIG. 10 is a perspective view of the near field communication antennasafter a second stamping of FIG. 9 with the release liner detached fromthe antennas;

FIG. 11 is a top view of a single near field communication antenna ofthe present disclosure after a second stamping;

FIG. 12 is a top view of a ferrite shield assembly sheet of the presentdisclosure;

FIG. 13 is a perspective view of a near field communication antennabiscuit on a fixture prior to application of a ferrite layer;

FIG. 14 is a perspective view of the near field communication antennabiscuit of FIG. 13 with the ferrite shield assembly sheet of FIG. 12being placed thereon;

FIG. 15 is a top view of the near field communication antenna biscuitwith a ferrite layer applied;

FIG. 16 is a top view of an individual near field communication antennaswith a ferrite layer applied;

FIG. 17 is a bottom view of an individual near field communicationantennas with a ferrite layer applied;

FIG. 18 is a top view of a pallet that can be used for manufacturing astamped antenna;

FIG. 19 is a perspective view of the pallet of FIG. 18;

FIG. 20 is a perspective view of the near field communication antennabiscuit of FIG. 2 being placed onto the pallet of FIG. 18;

FIG. 21 is a top view of a ferrite shield assembly sheet placed on afirst fixture or pallet;

FIG. 22A is a top view of the ferrite shields on the first fixture;

FIG. 22B is a top view of the plurality of antennas on a second fixtureor pallet;

FIG. 22C is a top view of a plurality of adhesive cards;

FIG. 23 is a top view of an adhesive card, an antenna, and a ferriteshield, showing the order that they are applied;

FIG. 24 is an exploded view of a completed antenna including a ferriteshield; and

FIG. 25 is a plan view of a sample manufacturing process for applyingthe ferrite shields.

DETAILED DESCRIPTION

The present invention relates to a method of manufacturing a stampedantenna.

FIG. 1 is a diagrammatic illustration of a sequential manufacturing linefor manufacturing a stamped antenna and provides a general overview ofthe manufacturing process. It should be understood by one of ordinaryskill in the art that this manufacturing process can be employed in themanufacture of any antenna that includes thin traces, e.g., antennasused in radio frequency identification tags, inductive chargingcircuitry, etc. The antennas are manufactured at a plurality of stationsthat are arranged sequentially about the manufacturing line 10. A supplyreel 12 feeds an antenna material, e.g., a thin sheet of copper such ascopper foil, to a first station 14 that includes a first precisionhigh-speed stamping press for performing a first partial stamping of theantenna. FIG. 2A is a top view showing a group of near fieldcommunication antennas 16 after a first partial stamping by the firststamping press. After the first stamping, the antennas 18 a-e includetie bars 20 and carriers 22 to add stability and support to thepartially stamped antennas. After each group of antennas, the coppersheet is cut so that a near field communication antenna biscuit iscreated having a group of antennas, e.g., five as shown in FIG. 2A. Thebiscuit 16 includes antennas 18 a-e connected with carriers 22 and aseries of tie bars 20 that extend between the antennas 18 a-e and withineach respective antenna 18 a-e. Further, the tie bars 20 within eachantenna 18 a-e, and between the antennas 18 a-e, support the antennas 18a-e and prevent the antennas 18 a-e from being misshapen. The biscuit 16also includes a plurality of pilot holes 24, which will be discussed ingreater detail.

FIG. 2B is a top view of an individual antenna 18 a from the near fieldcommunication antenna biscuit 16 showing the individual antenna 18 a ingreater detail. As can be seen in FIG. 2B, the antenna 18 a includes anintricate shape of thin traces 26 connected to two paddles 28 orcontacts. The traces 26 are interconnected by the series of tie bars 20and connected to the carriers 22. The series of tie bars 20 and carriers22 provide stabilization, support, and strength for the thin traces 26of the antenna 18 a so that the traces 26 can be further processedwithout risk of breakage. At a second station 27, the two contacts 28could be gold plated.

At a third station 29, a pressure sensitive adhesive (PSA) pad 30 isplaced onto a fixture 32 or jig. FIG. 3A is a top view of a PSA pad 30including a release liner 34. FIG. 3B is a perspective view of the PSApad 30 of FIG. 3A with the release liner 34 partially removed. FIG. 3Cis a perspective view of the PSA pad 30 with the release liner 34completely removed. Removal of the release liner 34 exposes a pluralityof adhesive areas 36, having the general shape of the antennas. The PSApad 30 includes a release liner 34, adhesive areas 36, and a pluralityof die cut holes 38. The PSA pad 30 of FIGS. 3A-3C includes fiveadhesive areas 36 to match the five antenna 18 a-e. The adhesive areas36 are located and shaped to match the five antenna 18 a-e such that theantenna traces 26 and contacts 28 are bonded with the adhesive areas 36.The plurality of die cut holes 38 could be positioned along theperimeter of the PSA pad 30. The die cut holes 38 match with any fixturepins 42 on the fixture 32 or jig, as well as the pilot holes 24 of theantenna biscuit 16, and facilitate alignment of the PSA pad 30 on thefixture 32, and alignment of the PSA pad 30 with the antenna biscuit 16.

FIG. 4 is a perspective view of a fixture 32 for receiving the PSA pad30 and the antenna biscuit 16. The fixture 32 includes a body 40 and aplurality of pins 42 for alignment of the PSA pad 30 and the antennabiscuit 16.

FIG. 5 is a perspective view of the PSA pad 30 on the fixture 32 of FIG.4. The PSA pad 30 is placed over the fixture 32 so that the plurality ofpins 42 are inserted into the die cut holes 38 of the PSA pad 30. Therelease liner 34 of the PSA pad 30 is removed prior to placing the PSApad 30 onto the fixture 32.

The antenna biscuit 16 is then transferred to the third station 29 to bealigned with the PSA pad 30 and the fixture 32. FIG. 6 is a perspectiveview of the group of antennas 16 of FIG. 1 on the fixture 32 having aPSA pad 30 already placed thereon. The plurality of fixture pins 42extend through the die cut holes 38 of the PSA pad 30 and facilitatealignment of the PSA pad 30 and the near field communication antennabiscuit 16. The near field communication antenna biscuit 16 is placedonto the fixture 32 so that the fixture pins 42 extend through the pilotholes 24. FIG. 7 is a top view showing the near field communicationantenna biscuit 16 and the PSA pad 30 on the fixture 32. As can be seen,the traces 26 of each antenna 18 a-e overlap an adhesive portion 36 ofthe PSA pad 30. The previously removed release liner 34 is then placedon top of the near field communication antenna biscuit 16 as shown inFIG. 8. Placing the release liner 34 over the near field communicationantenna biscuit 16 protects the PSA pad 30 during additional stampingprocesses.

The fixture 32, PSA pad 30 and antenna biscuit 16 are transferred to afourth station 44 for bonding the antenna biscuit 16 with the PSA pad30. The fourth station 44 includes rollers that provide pressure foractivating the PSA 30 and bonding the antenna biscuit 16 with the PSApad 30. Once bonded, the antenna biscuit 16, now with a PSA layer 30, isadvanced to a fifth station 46 that includes a second precisionhigh-speed stamping press for performing a second antenna stamping. Thesecond stamping press performs a second stamping operation on theantenna biscuit 16 wherein the tie bars 20 are stamped and removed fromeach antenna 18 a-e. The second stamping press stamps through the foilthat makes up the tie bars 20, the PSA bonded to the tie bars 20, andthe release liner 34. The carriers 22 will fall away upon stamping ofthe tie bars 20 because the carriers 22 are generally outside theadhesive area 36 of the PSA pads 30. As such, the second stampingoperation effectively removes each individual antenna 18 a-e from theantenna biscuit 16 so that each antenna 18 a-e is by itself, butsupported by the PSA pad 30. FIG. 9 is a top view of the antenna biscuit16, PSA pad 30, and release liner 34 after the secondary stamping. Theantenna biscuit 16 and PSA pad 30 cannot be seen because they arecovered by the release liner 34. As can be seen, the plurality of tiebars 20 and carriers 22 have been stamped out and removed. The secondstamping process can also stamp a plurality of guide holes 48 for futureferrite shield application, which will be discussed in greater detail.

Once the second stamping is complete the release liner 34 can be peeledaway, as shown in FIG. 10, which is a perspective view showing therelease liner 34 removed from the antenna biscuit 16. When the releaseliner 34 is removed, five individual and disconnected antennas 18a-ebonded to a single piece PSA pad 30 remain. In one embodiment, thePSA pad 30 may be cut so that each individual antenna 18 a-e isseparated from one another. FIG. 11 is a top view of an individualantenna 18 a after the second stamping and separated from the otherindividual antennas 18 b-e. The completed antenna 18 a no longerincludes a tie bar 20 connecting the traces 26 or the contacts 28. Thecompleted antennas 18 a-e can then be sent to a sixth station 50 wherethey are packaged for distribution.

In an alternative embodiment, the antenna biscuit 16 and PSA pad 30 ofFIG. 10, e.g., without the release liner 34, could be sent to analternative sixth station 52 where instead of being cut into individualantennas, they are instead bonded with a ferrite shield. FIG. 12 is aview of a ferrite shield 54 assembly sheet that may be used. The ferriteshield assembly sheet 54 includes a liner 56, a series of ferriteshields 58, and a plurality of pilot holes 60. The ferrite shieldassembly sheet 54 is generally sized, dimensioned, and arranged so thateach individual ferrite shield 58 generally overlaps a respectiveantenna 18 a-e of the antenna biscuit 16.

FIG. 13 is a perspective view of the antennas 18 a-e and PSA pad 30sub-assembly placed on a fixture, with the antennas 18 a-e facing upwardand the PSA pad 30 abutting the fixture 62. The fixture 62 includes abody 64 and a plurality of guide pins 66 that are aligned with andinserted into the guide holes 48 the PSA pad 30. As shown in theperspective view of FIG. 14, the ferrite shield assembly sheet 54 ofFIG. 12 is placed on to the fixture 62 such that the guide pins 66 ofthe fixture 62 are aligned with and inserted into the pilot holes 60 ofthe ferrite shield assembly sheet 54. The ferrite shield assembly sheet54 is oriented such that the series of ferrite shields 58 are facing thecopper antennas 18 a-e. When the ferrite shield assembly sheet 54 isplaced on the fixture 62, the ferrite shields 58 overlap the antennas 18a-e, such that there is one ferrite shield 58 for each individualantenna 18 a-e. The ferrite shields 58 are then bonded to the respectiveantenna 18 a-e by means that are known in the art, for example, a vacuumadhesive. Once bonded, the ferrite shield liner 56 can be removed,leaving a series of five individual antenna 18 a-e each having a ferriteshield 58 bonded thereto, as shown in FIG. 15. The antennas 18 a-e, heldtogether as a group by the PSA pad 30, can be cut into individualantenna 18 a-e and the PSA pad 30 can be removed. FIGS. 16-17 show anantenna 18 a having a ferrite shield 58.

FIGS. 18-20 show an alternative embodiment in which a pallet 70 is usedin place of the fixture 32. The pallet 70 includes a body 72, a handle74 extending from the body 72, a plurality of pilot holes 76, aplurality of guide pins 78, and a plurality of removed sections 80. Theplurality of pilot holes 76 are positioned to match guide pins of astamping machine so that the pallet 70 is properly aligned when engagedwith the machine. The plurality of guide pins 78 facilitate positioninga PSA pad 30, antenna biscuit 16, and ferrite shield assembly sheet 54during manufacturing. The guide pins 78 ensure that the PSA pad 30 andantenna biscuit 16 are located such that the tie bars 20, carriers 22,and portions that need to be cut by pressing are positioned over theremoved sections 80. The removed sections 80 allow a die to be pressedthrough the PSA pad 30 and the antenna biscuit 16, thus facilitatingremoval of the tie bars 20 and carriers 22.

FIGS. 21-25 shown another method for applying a ferrite shield layer.FIG. 21 is a top view of a ferrite shield assembly sheet 82 placed on afirst fixture or pallet 84. The ferrite shield assembly 82 includes aliner 86 and a plurality of ferrite shields 88. The ferrite shieldassembly 82 is placed on the first fixture 84 such that the ferriteshields 88 are face down on the first fixture 84, e.g., adjacent thefirst fixture 84, and the liner 86 is face up. The first fixture 84 caninclude a vacuum or magnets that hold the ferrite shields 88 in place.Accordingly, the liner 86 can be removed from the ferrite shields 88,and the ferrite shields 88 will be retained in place by the fixture 84.

FIG. 22A is a top view of the ferrite shields 88 on the first fixture84. FIG. 22B is a top view of the plurality of antennas 18 a-e on asecond fixture or pallet 90. FIG. 22C is a top view of a plurality ofadhesive cards 92. Each of the plurality of adhesive cards 92 includes abottom release liner (not shown), a top liner 94, an adhesive area 96,an two alignment holes 98. The bottom release liner is a continuousliner that spans one or more of the adhesive cards such as the fiveadhesive cards 92 shown, and is removed during assembly to expose theadhesive areas 96. The top liner 94 is cut into a square/rectangle thatextends beyond the edges of the adhesive area 96. The two alignmentholes 98 facilitate alignment of the adhesive cards 92 with a pick-uppad.

FIG. 23 is a top view of an adhesive card 92, an antenna 18 a, and aferrite shield 88, showing the order that they are assembled. As shownin FIG. 23, the adhesive card 92 is first applied to the antenna 18 a,and then the ferrite shield 88 is applied over the antenna 18 a and ontothe adhesive card 92. This application process is discussed in greaterdetail in connection with FIG. 25. FIG. 24 is an exploded side view of acompleted antenna 100 including a ferrite shield 88. The completedantenna 100 includes a plurality of layers that include, from top tobottom, the top liner 94, the adhesive area 96, the antenna 18 a, andthe ferrite shield 88.

FIG. 25 is a plan view of a sample manufacturing process for applyingthe ferrite shield 88. Once the PSA 30 is bonded with an the antennabiscuit at the fourth station 44 of FIG. 1, the antenna biscuit with PSAlayer 30 can be transferred to a loading station 102, where it is loadedonto a conveyor belt or track 104. The antenna biscuit is transferred toa second or complete stamping station 106 where the tie-bars are removedand the antennas are singulated by a second stamping process, which isin accordance with the fifth station 46 of FIG. 1, described above. Theindividual antennas are delivered by the conveyor 104 to a palletloading station 108 where the antennas are placed on a pallet or plate.The pallet could be configured like the pallet 70 shown in FIGS. 18-20.The pallet can hold any number of antennas, such as five antennas, forexample. The pallet with antennas is then conveyed to an assemblystation 110.

The assembly station 110 could include a robotic device 112, which couldhave 3-axis movement, an adhesive applicator 114, and a robotic cylinder116. The assembly station 110 receives the antennas and attaches theferrite shields 88. In preparation for applying the ferrite shields 88to the antennas, the adhesive applicator 114 removes the bottom liner ofthe adhesive cards 92, rolls the removed bottom liner onto a scraproller, and places each adhesive card 92 into a tray of the roboticcylinder 116. The robotic cylinder 116 transfers the adhesive cards 92to the robotic device 112. The robot device 112 could be a roboticpick-up pad that could be a vacuum pad attached to the end of an arm ofthe robotic device 112 to pick up the adhesive cards 92. The roboticdevice 112 includes pilot pins that engage the alignment holes 98 of theadhesive cards 92 and locate/align the adhesive cards 92. Once theadhesive cards 92 are ready for transferring, the robotic device 112moves the adhesive cards 92 into alignment over the antennas, which aretransferred by the pallet 70. The robot 112 then stamps the adhesivecards 92 onto the antennas, such that the adhesive areas 96 engage theantennas, and picks the antennas up. Next, the robotic device 112 movesthe adhesive card 92 and antenna sub-assembly over the first fixture 84containing the ferrite shields 88, and stamps down on the ferriteshields 88 to bond the ferrite shields 88 to the antennas and theadhesive cards 92. The antennas, including adhesive cards 92 and ferriteshields 88, are then transferred along the conveyor belt to apick-and-pack station 118 where the antennas are removed from theconveyor 104, scrap is removed, and the antennas are packaged.

Having thus described the invention in detail, it is to be understoodthat the foregoing description is not intended to limit the spirit orscope thereof. What is desired to be protected is set forth in thefollowing claims.

What is claimed is:
 1. A method of manufacturing an antenna, comprising:providing a sheet of metallic material; performing a first stamping ofthe sheet of metallic material to form at least one antenna, the atleast one antenna including at least one pilot hole, traces, contacts, acarrier connected to the traces, and at least one tie-bar connectedbetween the traces; placing the antenna stamped for a first time on afixture having at least one fixture pin, the fixture pin being insertedthrough the at least one pilot hole; placing a pressure sensitiveadhesive including at least one die cut hole on the fixture, the fixturepin being inserted through the at least one die cut hole and aligningthe antenna stamped for a first time and the pressure sensitive adhesivesuch that an adhesive region of the pressure sensitive adhesive ispositioned on the traces of the at least one antenna; bonding thepressure sensitive adhesive to the traces of the at least one antenna;and performing a second stamping of the at least one antenna and thepressure sensitive adhesive to remove the at least one carrier and theat least one tie-bar connected to the traces.
 2. The method ofmanufacturing an antenna of claim 1, wherein the first stamping formsmore than one antenna as a group connected by at least one tie-bar orthe carrier.
 3. The method of manufacturing an antenna of claim 2,wherein the pressure sensitive adhesive is a pressure sensitive adhesivepad having more than one pressure sensitive adhesive area.
 4. The methodof manufacturing an antenna of claim 3, wherein the more than oneantenna are separated from one another after the second stamping.
 5. Themethod of manufacturing an antenna of claim 1, wherein the carrierincludes at least one pilot hole and the pressure sensitive adhesiveincludes at least one die cut hole.
 6. The method of manufacturing anantenna of claim 1, wherein the fixture is a pallet.
 7. The method ofmanufacturing an antenna of claim 1, wherein the sheet of metallicmaterial is copper.
 8. The method of manufacturing an antenna of claim1, further comprising: bonding a ferrite shield to the at least oneantenna stamped for a second time.
 9. The method of manufacturing anantenna of claim 8, further comprising: placing the antenna stamped fora second time on a second fixture; placing the ferrite shield on a thirdfixture; bonding an adhesive to the antenna and removing the antennafrom the second fixture; placing the adhesive and the antenna on thethird fixture such that the antenna is placed on the ferrite shield; andbonding the adhesive to the ferrite shield; wherein the antenna ispositioned between the adhesive and the ferrite shield.
 10. The methodof manufacturing an antenna of claim 9, wherein the second fixture andthe third fixture are pallets.
 11. A method of manufacturing an antenna,comprising: providing a sheet of metallic material; performing a firststamping of the sheet of metallic material to form at least one antenna,the at least one antenna including traces, contacts, a carrier includinga pilot hole connected to the traces, and at least one tie-bar connectedbetween the traces; bonding a pressure sensitive adhesive to the tracesof the at least one antenna, the pressure sensitive adhesive including afirst and second die cut hole; performing a second stamping of the atleast one antenna and the pressure sensitive adhesive to remove the atleast one carrier and the at least one tie-bar connected to the traces;and bonding a ferrite shield to the at least one antenna stamped for asecond time, the ferrite shield including a pilot hole.
 12. The methodof manufacturing an antenna of claim 11, further comprising: placing theantenna stamped for a first time on a first fixture having at least onefixture pin, the fixture pin being inserted through the pilot hole;placing the pressure sensitive adhesive on the first fixture, thefixture pin being inserted through the first die cut hole; wherein thefixture pin aligns the first stamped antenna and the pressure sensitiveadhesive such that an adhesive region of the pressure sensitive adhesiveis positioned on the traces of the antenna.
 13. The method ofmanufacturing an antenna of claim 12, wherein the first fixture is apallet.